RSA_SIGN_HASH()

Procedural SQL (PSQL) StatementsAggregate Functions

`RSA_SIGN_HASH()`

PSS encodes a message hash and signs it with an RSA private key

Result type

VARBINARY

Syntax

RSA_SIGN_HASH (message_digest
  KEY private_key
  [HASH <hash>] [SALT_LENGTH salt_length]
  [PKCS_1_5])

<hash> ::= MD5 | SHA1 | SHA256 | SHA512

Table 1. `RSA_SIGN_HASH` Function Parameters
Parameter	Description
message_digest	Hash of message to sign.The hash algorithm used should match hash
private_key	RSA private key in PKCS#1 format
hash	Hash to generate PSS encoding;default is `SHA256`.This should be the same hash as used to generate message_digest.
salt_length	Length of the desired salt in bytes;default is 8;minimum 1, maximum 32.The recommended value is between 8 and 16.

RSA_SIGN_HASH performs PSS encoding of the message_digest to be signed, and signs using the RSA private key.

By default, OAEP padding is used.The PKCS_1_5 option will switch to the less secure PKCS 1.5 padding.

Warning

The PKCS_1_5 option is only for backward compatibility with systems applying PKCS 1.5 padding.For security reasons, it should not be used in new projects.

Caution

This function expects the hash of a message (or message digest), not the actual message.The hash argument should specify the algorithm that was used to generate that hash.

A function that accepts the actual message to hash might be introduced in a future version of Firebird.

PSS encoding

Probabilistic Signature Scheme (PSS) is a cryptographic signature scheme specifically developed to allow modern methods of security analysis to prove that its security directly relates to that of the RSA problem.There is no such proof for the traditional PKCS#1 v1.5 scheme.

`RSA_SIGN_HASH` Examples

Tip	Run the example of the `RSA_PRIVATE` function first.

select rdb$set_context('USER_SESSION', 'msg',
  rsa_sign_hash(crypt_hash('Test message' using sha256)
    key rdb$get_context('USER_SESSION', 'private_key'))) from rdb$database;

RSA_SIGN_HASH()

RSA_SIGN_HASH()

RSA_SIGN_HASH Examples

`RSA_SIGN_HASH()`

`RSA_SIGN_HASH` Examples